Particulate Matter (PM10)

Particulate matter is one of the six common air pollutants identified by the EPA as being critical to assessing environmental health of a place. Particulate matter comes in various sizes. The National Ambient Air Quality Standards (NAAQS) have separated particulate matter into two groups--PM2.5 (particles that are 2.5 microns or smaller in diameter) and PM10 (particles that are between 2.5 and 10 microns in diameter). The principal cause for decreased visibility is linked to PM2.5, whereas PM10 accumulates in the upper respiratory tract of humans and is thus thought to contribute to chronic bronchitis, decreased lung function, coughing, painful breathing and premature death (Greater Phoenix Regional Atlas: A Preview of the Region's 50-year Future, p. 39).

An exceedance of federal PM10 standards occurs when the 24-hour average is greater than 150 micrograms per cubic meter. Several areas in the state are classified as being in nonattainment status for PM10 by the Environmental Protection Agency (EPA) due to exceeding the standard; Maricopa County recently had its 2012 plan for reducing dust particles approved by the EPA, which will allow the county to shed its non-attainment status.

Readers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring site are not necessarily representative of the air quality for an entire county or urban area.

Data Quality Comments:

Data show the estimated exceedances of the standard (150 µg/m3) for a 24-hour average. Estimated exceedances are derived from the number of actual exceedances and the frequency of monitor reporting. These data include exceptional events, which is defined as an event that affects air quality, is not reasonably controllable or preventable, is an event caused by human activity that is unlikely to recur at a particular location or a natural event, and is determined by the EPA in accordance with 40CFR 50.14 to be an exceptional event. Although exceptional events may not be used by the EPA in determining nonattainment status, they contribute to poor environmental health.

Disclaimer: AirData reports are produced from a direct query of the AQS Data Mart. The data represent the best and most recent information available to EPA from state agencies. However, some values may be absent due to incomplete reporting, and some values may change due to quality assurance activities. The AQS database is updated daily by state, local, and tribal organizations who own and submit the data. Please contact the appropriate air quality monitoring agency to report any data problems.

Visualization Notes:

PM10 violations have been a consistent problem in Maricopa, Pinal, and Santa Cruz Counties. However, in 2006, the number of PM10 violations in Pinal County shot up dramatically. The number has been decreasing since then, as measures continue to be taken to control the problem. Many of these violations occur in the cities of Maricopa and Casa Grande and may be due to increased development as well as agricultural and feedlot sources. The causes of PM10 pollution in various counties, along with nonattainment area and attainment area maintenance plans, can be seen at [http://www.azdeq.gov/environ/air/plan/notmeet.html].

Readers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring site are not necessarily representative of the air quality for an entire county or urban area.

Visualization Notes:

This chart shows the average number of estimated exceedances per county, ignoring those stations that did not have violations. Monitors that did not record an exceedance are not included in these data.

Data Source

Readers are cautioned not to rank order geographic areas based on AirData reports. Air pollution levels measured at a particular monitoring site are not necessarily representative of the air quality for an entire county or urban area.